Olive-Leaf Extracts Modulate Inflammation and Oxidative Stress Associated with Human H. pylori Infection

Abstract

Helicobacter pylori (H. pylori) is one of the major human pathogens and the main cause of pathological damages that can progress from chronic gastritis to gastric cancer. During the colonization of gastric mucosa, this bacterium provokes a strong inflammatory response and subsequent oxidative process, which are associated with tissue damage. Therefore, the objective of this research was to evaluate the ability of two olive-leaf extracts (E1 and E2) to modulate the inflammatory response and oxidative stress in H. pylori-infected human gastric AGS cells. The obtained results showed that both extracts significantly decreased interleukin-8 (IL-8) secretion and reactive oxygen species (ROS) production in human gastric AGS cells. Both extracts also showed antibacterial activity against different H. pylori strains. HPLC-PAD-MS characterization demonstrated that extract E1 was mainly composed of highly hydrophilic compounds, such as hydroxytyrosol (HT) and its glucosides, and it was the most effective extract as an antibacterial agent. In contrast, extract E2 was composed mostly of moderately hydrophilic compounds, such as oleuropein (OLE), and it was more effective than extract E1 as an anti-inflammatory agent. Both extracts exhibited similar potential to decrease ROS production. These results show the importance of standardizing the extract composition according to the bioactive properties that should be potentiated.

Influence of In Vitro Gastric Digestion of Olive Leaf Extracts on Their Bioactive Properties against H. pylori

“…were identified unambiguously by co-elution and comparison with their retention time, order of elution, UV spectra, and pseudo-molecular and fragment ion masses of the corresponding reference substances, and quantified according to the calibration curves of each of them. The glucosides of 3,4-DHBA, 3,4-DHPE, and 3,4,5-THBA were identified tentatively by using their corresponding retention time, order of elution, UV spectra, pseudo-molecular, diagnostic fragment ion masses, and bibliographic data [13]. The 3,4-…”

“…Solutions of 10 mg/mL of water soluble E1 and alcohol soluble E2 extracts and their gastric digests (DE1 and DE2) at different pH were prepared in duplicate (n = 2), in water and methanol, respectively, and were analyzed by reverse-phase high performance liquid chromatography (RP-HPLC), coupled sequentially to photodiode array detector (PAD) and mass spectrometry (MS) with electrospray ionization source (RP-HPLC-PAD-MS(ESI)), as described by Silvan et al [13]. The glucosides of 3,4-DHBA, 3,4-DHPE, and 3,4,5-THBA were identified tentatively by using their corresponding retention time, order of elution, UV spectra, pseudo-molecular, diagnostic fragment ion masses, and bibliographic data [13].…”

“…Solutions of 10 mg/mL of water soluble E1 and alcohol soluble E2 extracts and their gastric digests (DE1 and DE2) at different pH were prepared in duplicate (n = 2), in water and methanol, respectively, and were analyzed by reverse-phase high performance liquid chromatography (RP-HPLC), coupled sequentially to photodiode array detector (PAD) and mass spectrometry (MS) with electrospray ionization source (RP-HPLC-PAD-MS(ESI)), as described by Silvan et al [13]. The glucosides of 3,4-DHBA, 3,4-DHPE, and 3,4,5-THBA were identified tentatively by using their corresponding retention time, order of elution, UV spectra, pseudo-molecular, diagnostic fragment ion masses, and bibliographic data [13]. The 3,4-DHBA glucoside was quantified as equivalents of 3,4-DHBA, the three 3,4-DHPE glucosides were quantified as equivalents of 3,4-DHPE, and the two 3,4,5-THBA glucosides were quantified as equivalents of 3,4,5-THBA.…”

“…Therefore, the use of alternative therapies that could enhance antibiotic activity or modulate inflammatory response to support H. pylori eradicative therapy appears to be reasonable. In this regard, extracts with bioactive properties obtained from food ingredients or food by-products are showed as potentially useful candidates in the complementary therapy against H. pylori [11][12][13][14][15].…”

“…Recently, we have reported that olive leaf extracts with different composition showed anti-inflammatory, antioxidant, and antibacterial activity against H. pylori. These properties were significantly related with the phenolic and secoiridoid composition of these extracts [13], which can vary depending on factors, such as olive variety and growing, climatic, and storage conditions. Oleuropein and hydroxytyrosol are mayor constituents of olive leaf extracts, followed by verbascoside, apigenin-7-glucoside, luteolin-7-glucoside, and tyrosol.…”